Fuel generator with diffusion ampoules for fuel cells

ABSTRACT

A system of two fuel ampoules that can deliver a reactant by diffusion through one of the ampoule walls to the other, such that when said reactant enters the second ampoule, it reacts with another reactant in said second ampoule, making hydrogen gas as a product. Both ampoules are stored in a fuel impermeable container. These ampoules used with small low power fuel cells which need a steady controlled uniform delivery of vaporous fuel such hydrogen and alcohols. This fueling system provides a simple safe fuel interactive system for small hydrogen fuel cells that prevents inadvertent hydrogen production by any single ampoule being exposed to water or typical consumer environments.

BACKGROUND OF THE INVENTION

[0001] Fuel cells directly transform chemical energy to electricalenergy by reacting electrochemically gas or liquids in the presence ofan electrolyte, electrodes and a catalyst. Our previous U.S. Pat. No.4,673,624 “Fuel Cell”, U.S. Pat. No. 5,631,099 “Surface Replica FuelCell, and U.S. Pat. No. 5,759,712 “Surface Replica Fuel Cell for MicroFuel Cell Electrical Power Pack” described a method of forming a fuelcell that efficiently utilizes expensive catalysts, is easily massproduced, and can be packaged for portable electronics.

[0002] A variety of methods for production and/or delivery of hydrogengas into fuel cells are known. Some of them include pressurized hydrogenstorage in cylinders and storage into metal hydride alloys, such asthose used in Ni—MH rechargeable batteries.

[0003] Needs exist to provide safe and convenient sources of hydrogenfuel for fuel cells at a low cost, especially in portable powerapplications.

[0004] A different way of creating and delivering this hydrogen is touse chemical hydride compounds that absorb water or other liquids orgases which react with the chemical hydride to form hydrogen. Thehydrogen then diffuses out and is delivered to the fuel cell or hydrogenconsuming device.

[0005] There are a variety of chemical hydrides which release hydrogenwhen combined with water. Their reaction with water can be described bythe following general equation:

MH_(x) +xH₂O→M(OH)_(x) +xH₂

[0006] where M is a metal of valence x. Examples of these chemicalhydrides include LiH, LiAlH₄, LiBH₄, NaH, NaAlH₄, NaBH₄, MgH₂, Mg(BH₄)₂,KH, KBH₄, CaH₂ and Ca(BH₄)₂ (Kong et. al). Kong et al. showed that LiH,LiAlH₄, LiBH₄, NaH, NaBH₄ and CaH₂ all deliver a large fraction of theirhydrogen capacity upon reaction with water vapor. Conversely, LiBH₄ andNaBH₄ were observed not to react with water vapor and there was noreaction with water until the powders were effectively dissolved. TheU.S. Army Mobility Equipment Research and Development Command developeda system in which liquid water flows from a reservoir into a chamberwhere it contacts a porous hydrophobic membrane. In this system, watervapor diffuses through the membrane and spontaneously reacts with thehydride to release hydrogen, which then flows out of the reactionchamber to the anode of the fuel cell. Hydrogen production is controlledby virtue of water being forced back into the water reservoir duringperiods of no load, when the hydrogen is not being consumed.

[0007] As another example, Millennium Cell has developed a chemicalhydrogen generator based on basic solutions of sodium borohydride(Amendola et al.). The generation of hydrogen is based on the reaction:

NaBH₄+2H₂O→NaBO₂+4H₂  (1)

[0008] Basic solutions of sodium borohydride were shown to be stable. Acatalyst (Ru) releases hydrogen when in contact with the solution andtherefore requires mechanical means to bring the solution into contactwith the catalyst. This adds complexity to the system.

[0009] This last case is a particular example of the more general casewhere NaBH₄ and water are chosen from a larger class of compounds A andB, respectively.

[0010] This new invention addresses the pre-existing problems.

SUMMARY OF THE INVENTION

[0011] A subject of this invention is to advance fueling systems such asdescribed in our U.S. Pat. No. 5,759,712 that has the fuel ampoulessealed in gas tight packages. An advance is to arrange a system of twoampoules or fuel components (A and B) such that when placed togetherproduce hydrogen and when separated do not. Diffusion regulationmechanisms are used to regulate the production rates, as well as thechoice of both A and B components. An objective is to make hydrogenfueling system safer for hydrogen consuming systems such as fuel cells.In products, an A ampoule and a B ampoule are placed in a cavity andsealed together. Reactants diffuse through the walls of one of theampoules into the other ampoule through the walls of the second ampoule.The reaction then produces hydrogen gas which diffuses out of the secondampoule.

[0012] Obvious applications of a small fuel cell are in those that arecurrently powered by batteries, especially rechargeable batteries. Bysafely encapsulating intrinsically energetic fuels with an interactivehydrogen release reaction, the fuel cells can have higher energy perunit mass, higher energy per unit volume, and be more convenient for theenergy user.

[0013] Our invention provides a safe, convenient, inexpensive andportable hydrogen generator which can be used to fuel a PEM fuel cell.Component A is chosen from chemical hydrides such as LiH, NaH, NaBH₄CaH₂ and LiAlH₄, among others. Component B may include, but is notlimited to, substances such as water, alcohols, organic and inorganicacids (e.g. acetic acid, sulfuric acid), aldehydes, ketones, esters,nitrites and superacids (e.g. polyoxotungstates), and combinationsthereof. Depending on the choice of component B, an appropriateselectively permeable membrane should be selected (e.g. silicone rubberfor methanol).

[0014] Our recently issued patent U.S. Pat. No. 6,194,095 describes howthe non-bipolar fuel cells can be packaged to form larger powersupplies. Our pending patent no. U.S. Ser. No. 09/821,053 describes anampoule of fuel that can be delivered at a controlled and constant rateby using the selective permeability of the fuel tank. In some fuel cellsa controlled release of hydrogen or other gas is also needed.

[0015] This patent describes a recipe where the choice of A and Binfluences the rate of hydrogen gas generation. More importantly, thispatent discloses a method for combining both chemicals without the aidof any mechanical means, thus resulting in a chemical hydrogen generatorwhich is safe, portable and inexpensive.

[0016] In our patent application No. U.S. Ser. No. 09/821,053, a liquidhydride solution is immobilized and its contact is controlled withcapillary wicking material. It does not have the feature of twocomponents in diffusion contact, instead describing physical contact ofa single fuel with a catalyst. Capillary wicking can be used toimmobilize any liquid reactants in a two component diffusion deliverysystem.

[0017] In our patent U.S. Pat. No. 5,759,712, a vapor phase transport toa hydrophilic outer surface of a gas manifold is described. Selectivelypermeable membranes in proximity to the fuel cell are described fordelivering reactants and products. Fueling is done by breaching a fueltank and wicking fuel, which is then transported to the fuel cells inthe vapor phase. Breaching this fuel tank can lead to spilling of fuelwhile liquid contact needs to be maintained with the fuel in the fueltank. Thus, as the fuel tank runs low on fuel some of the fuel may notbe in liquid contact and will be unused. To achieve wicking fueldelivery, the fuel needs to be fluid and mobile thus increasing thepossibilities of leakage from the fuel ampoule. Gravity can affect thedelivery of a liquid fuel. Achieving a good liquid seal on methanol fuelcan lead to complex and costly sealing mechanisms for the fueling systemand the fuel cell system. Small leaks of liquid fuel compared to vaporloss through the same hole can have a far greater detrimental effect onthe air electrode and total fuel loss.

[0018] In our pending patent U.S. Ser. No. 09/208,745, the fuel cell andfueling ampoules are shown being placed in proximity to each other witha diffusion mat. The fuel tanks are described as a liquid wick or fluidmotion fueling. Fuel diffusion from the fuel tanks is not described.Plastic blister packaging of the fuel tanks does not indicate thesealing properties of the package, nor individual sealing. Porousfillers are described as being in the fuel tanks, but not as diffusiondelivery means.

[0019] Hydrogen Gas Generation

[0020] Chemical hydrides are known to react with water and give offhydrogen gas as a product. Reaction (1) shown above serves as anexample. In general, hydrogen generation occurs when the hydride ionreacts with a proton from another source. Water is the most commonsource of protons used, and hence its reactions with chemical hydrideshave been extensively studied and are well documented. Additives whichreduce the pH of the aqueous solution result in a higher rate ofhydrogen generation. Conversely, raising the pH to an appropriate levelcan stabilize sodium borohydride solutions, effectively lowering thereaction rate to the point where almost no hydrogen evolves.

[0021] Other reactants may be used instead of water. For example:

NaBH₄+4CH₃OH→Na[B(OCH₃)₄]+4H₂  (2)

[0022] We have carried out this reaction in our laboratories and foundthat the rate of hydrogen generation in the methanolysis reaction isconsiderably higher than in the hydrolysis reaction. As an example, thepowder form of NaBH₄ can be mixed as a slurry in a silicone rubber mixto be encapsulated. Water or methanol diffuse through the siliconerubber to the NaBH₄ and the generated hydrogen can diffuse out. Anencapsulated cylinder with water or methanol and a separate encapsulatedNaBH₄ cylinder could be placed together in the fuel manifold of a fuelcell to generate hydrogen. We have found this vapor delivery system atroom temperature and conditions to be very slow and unsteady with wateras the reactant. However with methanol vapor it is immediate and steady.We have tested the produced gas in a residual gas analyzer and confirmedthat the product gas is hydrogen, as expected from reaction (2).

[0023] This reaction system allows us to package the reactants as an ABsystem of two ampoules which separately do not make hydrogen at asignificant rate. We have also found that ethanol and isopropanol do notsignificantly react with NaBH₄.

[0024] Our pending patent application U.S. Ser. No. 09/821,053, thedisclosure of which is incorporated herein by reference, discloses amethod of using a selectively permeable membrane to diffuse selectedchemical species (e.g. methanol through silicone rubber) to provide fuelfor a fuel cell. That invention is herein expanded by including aseparate component, namely a chemical hydride contained in an ampoule,which reacts which said diffused species producing hydrogen gas whichcan then be used to fuel a PEM fuel cell.

[0025] Other reactions may be used to generate hydrogen. Alkaline,alkaline earth metals and metals from Groups IIIA and IVA may react withwater, alcohol or dilute acids to liberate hydrogen. The metals may beencapsulated in a matrix and the reactant (water, methanol, dilute acid)allowed to diffuse in through a selectively permeable membrane.

[0026] The reaction of the hydrides with water produces basic solutionsand compounds. When the product is a strong base this can be neutralizedwith carbon dioxide to form a carbonate and water. Other alternativesare the reactions with acids. This makes available more water for thereaction with the hydride and neutralizes the caustic base. The carbondioxide could come from the direct methanol or hydrocarbon utilizingfuel cell. In some cases by making water available from the reactionthis would be a net gain in the energy per unit mass for the system. Anideal combination might be a hydrocarbon which results in hydrogen gasand a carbonate product when combined with the chemical hydride. Afueling system is made up of two diffusion ampoules which slowly diffuseinto the other to produce hydrogen gas and solid encapsulated carbonateproducts when placed within an enclosure. As an example, consider thereaction of water with lithium hydride:

LiH+H₂→LiOH+H₂  (3)

[0027] A subsequent reaction takes place between LIOH and CO₂:

LiOH+CO₂→Li₂CO₃+H₂O  (4)

[0028] The water resulting from (4) can react with unreacted LiH asshown in reaction (3) to further produce hydrogen gas. At the same time,a more benign end product (lithium carbonate) is produced.

[0029] In our previous patents U.S. Pat. No. 5,631,099 and U.S. Pat. No.5,759,712, the carbon dioxide exhaust can diffuse out through aselectively permeable membrane or the fuel tank itself. This feature cancontrol reaction (4). We have found that a simple gaseous diffusionroute such as a capillary tube can effectively exhaust product gases andmaintain gas pressure equilibrium across the fuel cells. The capillarytube can also function as a controlled leak for the beneficialin-leakage of oxygen to the fuel electrode.

[0030] The production of fuel such as hydrogen from a chemical hydridecan be regulated by delivery of moisture or acid. A valve or pump canused to regulate moisture from a tank containing the moisture to thesecond tank containing the hydride. This is an AB system where the twotanks work together. The moisture can be also very useful to maintainthe humidity for the fuel cells. Thus all the separate parts can form aninteracting system. The moisture valve can be a membrane with smallcontrollable apertures, or a gap between the tanks that is increased todecrease the delivery of reactants and is decreased to increase thedelivery of reactants.

[0031] Hydrogen ion-drag pumping through a membrane can be used to dragwater and solvents from one ampoule to the other. This can act as asolid state pumping system to move reactants. The amount of reactantmoved across the membrane is proportional to the electrical currentgoing through the membrane. Thus, the production of hydrogen can becontrolled through the electrical current through the separatingmembrane. Examples of a suitable membrane are Nafion withplatinum-catalyzed electrode on either side.

[0032] Another feature is to add a separate catalyst mixed with thehydride to increase the hydrogen production rate. Noble metal catalysts(e.g. Pt, Ru) and transition metals in general are particularly suitableto perform this function. Other suitable catalysts are substances suchas Co₂B, CoCl₂, CuCl₂, NiCl₂, Fe₂ when mixed with NaBH₄ powder.

[0033] Selectively permeable membranes

[0034] By having a selectively permeable fuel tank wall, the fueldelivery can have the advantageous effect of delivering fuel at aconstant rate throughout its life cycle. Component B may be made up oftwo or more chemicals, one or more of which may react with the chemicalhydride. If the membrane had similar permeability to the main chemicalin component B (i.e. the fuel) compared to a minority chemical incomponent B, the latter would diffuse in while the former diffused out.The presence of this minor chemical would drop the fuel vapor pressureand reduce the rate at which fuel can diffuse out. Thus, the rate offuel delivery would gradually drop. As an example, our measurements onsilicone rubber membranes show a molecular diffusion rate difference formethanol over water of 20 to 36 times. In performance tests with a smallampoule containing 95% methanol and 5% water with a silicone rubbermembrane, the fuel delivery system is effective in delivering fuel withonly a small fraction of the original fuel volume left as water in thefuel container.

[0035] Mixed fuels in component B made up of chemicals such as methanol,formaldehyde, formic acid and water could be used in the fuel ampoule.If these additives are permeable through the fuel ampoule they will alsobe delivered according to their respective rates and concentrationgradients. The fuel ampoule material could also be chosen or designed bya mixture of materials to have a permeability that allows the fuel to bedelivered at the rate ratio matching that of the fuel. An example is anampoule wall material that has a 1:1 diffusion rate for methanol overwater. Thus, if fueled by a 1:1 fuel mixture and assuming a low exteriorconcentration of both, the diffusion delivery system would deliver fuelat a 1:1 concentration.

[0036] The process of enhancing the selective vaporization of fuel froma membrane is called per-evaporation. It essentially increases theevaporation of that fuel. The ampoule membrane may use this effect whenthe fuel concentration is low. It can keep the fuel concentration higherat the fuel cell than it would be without the fuel ampoule selectivelypermeable membrane.

[0037] The tank walls can be made of composite materials. Examples arefiberglass cloth and silicone rubber, where the fiberglass cloth givesmechanical strength and the silicone rubber has high diffusion rateproperties. The mechanical and diffusion properties of the fuel tankscan be adjusted to reflect the blend of materials and components makingup the fuel system. The tanks may also be made in layers. One option isto make the outer layer have the highest diffusion resistance and have asingle fuel such as methanol, with the interior having rapid diffusion.This would give the fuel delivery a flat output with time, matching thevapor pressure of the fuel liquid, and then a steep decline as theremaining vapor diffuses out of the interior materials and voids.

[0038] Incorporating electrical and mechanical diffusion control intothe fuel ampoule or between the fuel ampoule and the fuel cell allowsthe membrane diffusion to have a feedback mechanism to adjust toconsumption demands by the fuel cell, or to different environmentalconditions around the system. Possible mechanisms are drawing fuel usingionic drag through a membrane, piezoelectric operating of microapertures in the membrane, or impermeable membranes that act asapertures which can be adjusted to a specific opening path between thefuel ampoule and the fuel cell, or alternatively a fan.

[0039] The permeability of the fuel ampoule can vary with temperature.This property can be used to match the fuel cell consumption rate as thetemperature increases. The permeability rate can also be chosen to notrise as much as the fuel cell consumption rate to keep the fuel cell athigher temperatures using more fuel than necessary. This could be thecase in power applications where the power delivery is constantregardless of the temperature environment.

[0040] Molecular filtration can be used to keep impurities that can bedissolved in the fuel or come with the fuel to be left in the fuelampoule. This feature can be used to allow a fuel of low purity. Thefuel cell may also be protected by using the same principle. Thehydrogen gas generated inside the ampoule with the chemical hydride maybe filtered using a selectively permeable membrane made of palladium oran alloy thereof before the hydrogen fed to the PEM fuel cell. Thiskeeps impurities from affecting fuel cell performance.

[0041] The vapor fuel delivery and selective permeability of the ampoulealso have the effect of filtering the fuel. Additives such as dyes,flame colorizers and bitterants can be added to the fuel to make thefuel safer and possibly aesthetically pleasing to consumers. Addingwater absorbing chemicals can be added to the fuel to maintain the vaporpressure of the fuel. The interior of the tank could have a filler, suchas cellulose sponge, that has a higher diffusion rate to fuel than thewalls but would keep liquid fuel from being accessible even if the fueltank is ruptured or crushed.

[0042] By simply being able to remove the fuel tank from a sealedcontainer and sliding it into a chamber without alignment necessities, asystem with large dimensional tolerances where the user can close thecover is very simple and makes it convenient and low error prone.

[0043] The fuel tank as it uses fuel, if it has selective fuel delivery,will mechanically collapse. This fuel tank collapse can be used to forma mechanical fuel status indicator. A color stripe could be used thatmoves by a viewing window the fuel ampoule could be used. The fuel tankitself can be tinted to give a visual indication of fuel level. The fuelcan have colored dyes so that as the fuel is used it will give a colorchange indication of fuel status since the remaining fuel will bedarker. The fuel ampoule can also have materials, such as salts, thatproduce an opaque interior or color change in the fuel ampoule as thefuel is used.

[0044] Safety

[0045] An important feature of our invention is that the chemicalhydrides, traditionally thought of as dangerous can be safelyimmobilized in a number of ways.

[0046] The first is to contain the reactants inside a porous bag ormaterial. The powdered hydrides are contained within a hydrophobicporous plastic such as microporous polypropylene. In the event that thebag is dropped in water, only vapor contact with the hydride is made.The liquid fuel can be held in a container that has porous walls thatwill gradually wick the fuel to the surface of the container.

[0047] The second is to employ a container which can be a wicking spongematerial such that the chemical hydride or fuel are distributed throughit.

[0048] Another way is to employ a container which can have a pore freematerial that surrounds the liquid or solid fuel. Delivery of reactantswould be by diffusion through this material and may be selective, e.g.such as the preferential permeability of silicone rubber to methanolover water.

[0049] Yet another method employs an ion-exchange membrane. The fuelscould be reacted with an ion exchange material making them chemicallyattached to a surface or polymer. Both A and B fuels could be held bythe ion exchange materials.

[0050] Packaging

[0051] The next challenge is to package the diffusion system to workwith fuel cells or other devices and maintain the desired flow rate. Apotential problem is that the delivery rate of component B to theampoule which contains component A will be uneven depending on where theindividual particles of the latter are within their ampoule. Moleculesof component B will react first with those particles in the adjacentampoule closest to the selective membrane. This may have the effect thatthe rate of hydrogen production decrease with time. To compensate forthis, the diffusion wall encapsulated materials or homogenous materialcomposites can be perforated with small channels. The diffusion wallscan also have their highest resistance concentrated at the surface. Wehave found in experiments that the encapsulation can gradually breakapart as the reaction proceeds opening up further in diffusion routes. Afan or pump system that forces moist gas or fluid through the materialcan be used to increase the interaction of the water and the hydrides.With a feedback loop to this fan the output of the generator can adjustthe production rate to match the consumption rate. The small perforationhydrophobic pores in silicone rubber keep liquid water from being ableto penetrate and increase the production rate. The encapsulation canalso be designed to have an outer skin that is the predominant ratelimiting diffusion barrier and where the interior of the encapsulationhas a relatively high diffusion rate.

[0052] An unusual design of a reactor that mixes various features of theabove description and our previous pending patent No. U.S. Ser. No.09/821,053 is to encapsulate the dry reactant in the form of a longcapillary tube or tube bundle and a liquid filled capillary tube or tubebundle. Each of these capillary tubes can form a separate ampoule. Whenthe two ampoules are pressed together contact is made with a liquidfilled capillary tube and the dry reactant ampoule. Diffusion of liquidand direct liquid contact is forced into the dry hydrophobic reactanttubes by static pressure on the back of the liquid reactant tubes. Theliquid reactant will diffuse into the walls of the tube and producehydrogen which can diffuse back out through the walls of the tube.Bubbles will form and grow in the liquid and reactants and drive a waterdroplet through the long capillary tube until the droplet is broken. Theflow of produced hydrogen will continue to push forward the liquidreactant vapor. A small pump or static pressure against the gas pressurein the back of the liquid capillary tube can control the reactantdelivery. When the evolved gas pressure is high, it will force theliquid back out of the dry reactant capillary tubes to the source tube.This design does not have the capability to fully shut off the reactiondue to the diffusion though the capillary tubes, but if either reactorhas a long diffusion length of non reactant between each other this canbe effective in reducing the reaction to a low rate.

[0053] The storage container of the permeable fuel container needs to beimpermeable to the fuel. This container could be a disposable bag withmetal coatings or coatings such as Aclar® (Honeywell Specialty Films, POBox 1039, 101 Columbia Road, Morristown, N.J. 07962) PVDF polyvinylidenefluoride plastic. This tank could also be made of composite materials,such as PET plastic polyethylene terephthalate with an Aclar coating.The storage container could be a heat sealed bag with a tear point toallow the consumer to easily open. The essential parallel is that ofpackages for foods and ink jet cartridges.

[0054] These and further and other objects and features of the inventionare apparent in the disclosure, which includes the above and ongoingwritten specification, with the claims and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0055]FIG. 1 schematically shows the basic diffusion reaction system.

[0056]FIG. 2 schematically shows two encapsulated diffusion ampoulesystem.

[0057]FIG. 3 schematically shows a water-ion drag for diffusionregulation.

[0058]FIG. 4 schematically shows a diaphragm valve diffusion regulatedsystem.

[0059]FIG. 5 schematically shows a micro-valve regulated diffusionsystem.

[0060]FIG. 6 schematically shows a diaphragm pumped system.

[0061]FIG. 7 schematically shows a gas pumped circulation system.

[0062]FIG. 8 schematically shows an elastic wall diffusion regulator.

[0063]FIG. 9 schematically shows details of open elastic valve.

[0064]FIG. 10 schematically shows details of closed elastic valve.

[0065]FIG. 11 schematically shows the gas pumped circulation system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] The construction of a two ampoule fueling system is shown inFIG. 1. The volatile reactant ampoule 1 can be made of a polyvinylalcohol sponge (PVA Sponge; Shima American Corporation, 171Internationale Blvd., Glendale Heights, Ill. 60139) or cellulose sponge,soaked with methanol and water. Within the ampoule container 7 a solidreactant such as sodium borohydride is mixed within a material that ishighly permeable to methanol such as a silicone rubber compound (AB mixGE silicones: RTV6166A silicone polymer and 6166B curing agent GESilicones GE Company, Waterford, N.Y. 12188). This ampoule can be formedby mixing the sodium borohydride powder with this two component siliconeand curing the mixture at 60° C. in an oven. The silicone rubbermaterial AB mix GE silicones were chosen because they did not have waterin the cure, and the silicone rubber is approximately 40 times morepermeable to methanol compared to water. The hydrophobic nature of thesilicone rubber also prevents liquid water from penetrating or wickinginto the ampoule 3. Thus the embalmed sodium borohydride ampoule 3 hasvery low reactivity to liquid water if accidentally immersed in water.The two ampoules 1, 3 are separated by a selectively permeable membrane2. This membrane 2 can be constructed of a fiberglass mat such asFreudenburg Eglass mat T-1785 (Freudenburg Non-Wovens Ltd., 221 JacksonSt., Lowell, Mass. 01852) impregnated with silicone rubber adhesive (GEsilicones RTV 118) and compressed between low density polyethylenesheets. This results in strong silicone rubber membranes that are 25 to200 microns thick. The membrane is held in a gas tight frame of thecontainer 7 separating the two reactant ampoules 1 and 3. At the gasexit of the container 7 a filter 5 covers the exit port 4 to filter thegas of particulate or unreacted materials. This filter 5 could be madeof a porous polyethylene (0.03 micron pore; Mobil Chemical Company,Films Division, 729 Pittsford-Palmyra Rd., Macedon, N.Y. 14502) with submicron pores. The filter 5 could also have selective permeabilityproperties such as a thin palladium metal foil or a pore-free transitionmetal film supported on a substrate to filter the hydrogen 21 from thevolatile reactants 6. In operation this system is expected to havecontainer 7 open; then the two ampoules 1, 3 are inserted, and thecontainer 7, is resealed. Methanol and water will diffuse from thevolatile ampoule 1 through the separating membrane 2 and into the solidreactant ampoule 3. Hydrogen gas 21 is produced in the solid reactantampoule 3 and it diffuses out of the ampoule, through the exit filter 5and out the exit port 4.

[0067] In FIG. 2 a similar system as the membrane separated system isshown as in FIG. 1, except that there is no separating membrane 2. Thetwo ampoule walls 8 and 12, are now the selective diffusion mechanism.The ampoules 8, 12 can be made out of silicone rubber enclosing areactant filled sponge. In the volatile reactant ampoule 8 methanol fuelfills a sponge material such as PVA or cellulose. In the dry reactantampoule 12 sodium borohydride powder 11 is packed into an open cellurethane foam or embalmed in silicone rubber. In operation the twoampoules 8, 12 are placed together inside the fuel container 7, and thecontainer is sealed. The volatile reactant 8 diffuses into the powderampoule 12. The volatile reactant reacts with the chemical hydridepowder 11 in the powder ampoule 12, and hydrogen gas is produced. Thehydrogen gas diffuses out of the powder ampoule 12 into the interior 10of the container 7, and the hydrogen gas 21 goes through the exit filter14 and out of an exit port 13. The exit filter can be a porous membranesuch as porous polyethylene (Mobil Chemical Company, Films Division, 729Pittsford-Palmyra Rd., Macedon, N.Y. 14502) or expanded PTFE (CorningCostar, One Alewife Center, Cambridge, Mass. 02140). Products of watervapor and carbon dioxide from the fuel cell or consuming device 90diffuse back up the outlet tube 13 and through the exit filter 14. Theseproducts react with the chemical hydride in ampoule 11, 12 to producemore hydrogen. The hydrogen production of this device could be regulatedthrough changing the gas separation gap 10 between the ampoules 8, 12,and the diffusion length through the exit filter 14 and exit tube 13 forthe product 91 interactions with the fuel cell 90. The gas separationgap 10 is a diffusion limiting point in the system such that, if thecontainer walls 7 are flexible and the ampoules 8, 12 are attached tothe walls, the ampoules will move apart when the internal pressureincreases, subsequently increasing the diffusion path 10 between theampoules and reducing the hydrogen production rate.

[0068] In FIG. 3 a system that uses a ion-drag cell to move water andmethanol from the volatile ampoule to the chemical hydride ampoule isshown. The volatile ampoule is constructed as a silicone rubber walledampoule 15. It is filled with a sponge material such a PVA foamsaturated with water and methanol 16. This ampoule is placed in the fuelsystem container 26. The second ampoule is a silicone rubber walledampoule 19, filled with sodium borohydride powder and silicone rubbercompound (AB mix GE silicones: RTV6166A silicone polymer and 6166Bcuring agent) 18. The membrane electrode assembly 23, 17, 25 separatingthe two ampoules 15, 19 is made up of a Nafion membrane 17 with sputterdeposited electrodes 23 and 25 on either side of the membrane 17. Theflow of hydrogen ions from the electrode 25 through the electrolyte 17to 23 is regulated by the electrical current flow through the membrane17. Hydrogen gas is converted to hydrogen ions on the catalyticelectrode 17. These ions travel through the Nafion electrolyte 17carrying with them 5 to 7 water or methanol molecules with each ion.When the hydrogen ions reach the other side of the membrane 17, twoprotons and two electrons make one hydrogen molecule on the catalyticelectrode 23, and water and methanol evaporate from the electrode. Thevoltage and subsequent current on the electrodes 23, 25 comes from anexternal electrical feedback loop with the fuel cell or device thatneeds hydrogen on demand. Typically the current though the ion-drag cellwould be proportional but smaller than the current output of the fuelcell. The wires 38 and 39 are attached to the catalytic electrodes 23,25. Water, methanol and hydrogen from the surface of the cathodeelectrode 23 will diffuse through the ampoule wall 19 to the sodiumborohydride powder a silicone rubber compound 18 in ampoule 19 andcreate hydrogen by hydrolysis. The hydrogen created then diffuses thoughthe porous material and flows through the exit filter 22 or recyclesthrough a long diffusion path 24. The recycled hydrogen will go throughthe ion-drag cell 23, 17, 25. The exit filter 22 can be formed out ofporous membranes such as expanded PTFE (Filinert, Corning CoStar) or aselectively hydrogen permeable membrane formed by films of platinum onpalladium silver alloy and platinum on a etched nuclear particle trackmembrane (Nuclepore, Corning Corstar). The membrane is embalmed insilicone rubber film and is sealed to the exit of the container 26. Thefiltered hydrogen 21 exits the container 26 through a vent hose 20 to afuel cell or device needing hydrogen gas.

[0069] In FIG. 4 a binary chemical reaction system is shown with adiaphragm valve regulating the reaction diffusion between the tworeactant ampoules. An ampoule of the volatile reactant 28 is placed inthe container 27. This ampoule 28 is a PVA sponge saturated withmethanol and water. A pore free diffusion membrane 29 and a porousmembrane 35 are placed between the ampoule 28 and valve aperture 34.This drawing shows a single aperture 34 for simplicity in the drawings,but in actual devices an array of apertures spaced out over theseparating wall 58 would be expected. On the other side of theseparating wall 58 a selectively permeable membrane to methanol andwater over hydrogen 30 is placed. This selectively permeable membrane 30made of silicone rubber is 100 microns thick and is sealed to thecontainer walls 27. The selectively permeable membrane 30 and has asmall sealing disk 37 made with Viton rubber to seal with the valveaperture 34. The Viton rubber has low permeability to methanol andwater. A second ampoule is formed by a mixture of sodium borohydridepowder and silicone rubber compound 31 (AB mix GE silicones: RTV6166Asilicone polymer and 6166B curing agent). A gas exit filter 33 can beformed out of porous membranes such as expanded PTFE (Filinert, CorningCoStar) or a selectively hydrogen permeable membrane formed by films ofplatinum on palladium silver alloy and platinum on a etched nuclearparticle track membrane (Nuclepore, Corning Corstar). The membrane isembalmed in silicone rubber film and is sealed to the exit of thecontainer 27. The filtered hydrogen 21 exits the container 27 through avent hose 32 to a fuel cell or device needing hydrogen gas. A longdiffusion vent gas line 36 is placed through the container wall 27,venting gas from the porous membrane 35. This vents to the atmosphere tolet the selective permeable membrane 30 expand and contract with thepressure and gas generated by the sodium borohydride ampoule 31. Whenthe hydrogen pressure from the sodium borohydride ampoule 31 is high theselective permeable membrane 30 will expand and press the sealing disk37 against the sealing aperture 34. This will seal off the diffusion ofmethanol and water from the volatile source ampoule 28 to stop furtherreaction with sodium borohydride ampoule 31 and the production ofhydrogen. When the hydrogen pressure drops the selective permeablemembrane 30 will move away from the sealing aperture 34, and methanoland water can diffuse through the membrane and react with the sodiumborohydride ampoule 31. This then leads to hydrogen production and thepressure rising. Thus a pressure regulated hydrogen production operates.

[0070] In FIG. 5 two reacting ampoules are separated by a microvalvedseparating wall. The volatile ampoule 40 is placed in the container 46.This ampoule is formed by enclosing a PVA sponge saturated with methanoland water with a silicone rubber container. An ampoule of sodiumborohydride powder and silicone rubber compound 42 (AB mix GE silicones42: RTV6166A silicone polymer and 6166B curing agent) is placed on theother side of the microvalved 41 separator wall 59. The micro valves 41are placed over apertures 45 in the separator wall 59. The micro valves41 are actuated by electrical or mechanical feedback system from thefuel cell or device. When the micro valves 41 are opened, the volatilereactants methanol and water diffuse to react with the sodiumborohydride ampoule. When the micro valves are closed or partiallyclosed, they stop or throttle down the diffusion of the volatilereactants and thus adjust the production of hydrogen. An exit filter 44can be formed out of porous membranes such as expanded PTFE (Filinert,Corning CoStar) or a selectively hydrogen permeable membrane formed byfilms of platinum on palladium silver alloy and platinum on a etchednuclear particle track membrane (Nuclepore, Corning Costar). Themembrane is embalmed in silicone rubber film and is sealed to the exitof the container 46. The filtered hydrogen 21 exits the container 46through a vent hose 43 to a fuel cell or device needing hydrogen gas.

[0071] In FIG. 6 a system that uses a diaphragm pump to circulatehydrogen gas saturated with methanol and water vapor is shown. Anampoule 52 is made as a perforated PVA sponge saturated with methanoland water 53. The sponge 52 has gas channel perforations and is placedinside the container 48. The second ampoule 49 is formed as a moldedampoule, with gas channel perforations, by mixing sodium borohydridepowder 56 and silicone rubber compound (AB mix GE silicones 42: RTV6166Asilicone polymer and 6166B curing agent) and filling and separating froma mold. Between the two ampoules 52, 49 a diaphragm pump 50 is placed sothat it is sealed against the container walls 48, forming a diffusionbarrier when the pump is not running. The diaphragm pump is run byvibrating the diaphragm wall 50. When the diaphragm 50 moves away fromthe second diaphragm wall 72, hydrogen gas mixed with methanol and wateris drawn into the cavity between the diaphragms 73 through the inletvalve 51. When the diaphragms 73 and 72 move toward each other, the gasflows out of the cavity between the diaphragms 73 and out through theexit valve 55. The methanol, water and hydrogen gas move through thechemical hydride ampoule 49. Hydrogen gas is produced, while the waterand methanol are removed from the ampoule 49. The hydrogen gas stream 21with some methanol vapor flows to the fuel cell 90 though exit tube 74.Unused hydrogen, carbon dioxide and water vapor from the fuel cell 90flow through inlet tube 57 and through a long diffusion route 54. Themoisture and carbon dioxide carried by the hydrogen flow 21 back to theampoule 52, supplementing the volatile reactants from the volatileampoule 52. The hydrogen gas stream then passes through the gas channelsof the volatile ampoule 52, absorbing methanol and water and repeatingthe process. The diaphragm pump is controlled by a feedback loop to thefuel cell or hydrogen consuming device. The output of hydrogen isproportional to the flow rate of reactants through the pump. When thepump is not operated, methanol vapor diffuses back through the channel54 to the fuel cell 90 and runs the fuel cell at a lower performancelevel than with hydrogen gas 21. Thus, the hydrogen generation can beused during needs of high power, and the low level loads can run onmethanol vapor and a small amount of hydrogen produced by diffusion ofmethanol through the channels 54 and 74.

[0072] In FIG. 7 a system that uses a fan 61 to circulate hydrogen gassaturated with methanol and water vapor is shown. An ampoule 70 isformed as a perforated PVA sponge saturated with methanol and water. Thesponge 70 has gas channel perforations 71 through the sponge. The sponge70 is placed inside the container 68. The second ampoule 65 is formed asa molded ampoule, with gas channel perforations 64, by mixing sodiumborohydride powder and silicone rubber compound (AB mix GE silicones 42:RTV6166A silicone polymer and 6166B curing agent) and filling andseparating from a mold. Between the two ampoules 70, 65 a wall 62 andfan 61 are placed so that they are sealed against the container walls68, forming a diffusion barrier when the pump is not running. When thefan 61 is run by electrical energy, hydrogen gas mixed with methanol andwater is blown through the sodium borohydride ampoule 65 channels 64 andaround 66. Sodium borohydride reacts with the methanol and water andproduces hydrogen gas 21. The hydrogen gas flows though a filter ofexpanded PTFE 67. Part of the hydrogen gas 21 flow returns through along diffusion route 69 to the volatile ampoule 70, and the rest exitsthrough a tube 68 to the fuel cell or hydrogen consuming device. Thissystem will produce hydrogen gas 21 proportional to the methanol andwater flow rate through the fan 61. Thus, the controlling the fan 61speed controls the hydrogen 21 production rate.

[0073]FIG. 8 shows a system that controls the production of hydrogen bycontrolling diffusion of reactants between ampoules with a valve that isclosed by the wall tension in the container. The volatile reactantampoule is formed by enclosing a methanol and water saturated PVA sponge89 with silicone rubber membrane 88, 10 to 200 microns thick. Thevolatile reactant ampoule 88, 89 is placed inside the Viton™ rubberenclosure 80. The second ampoule 82, 86 is formed as a molded ampoule bymixing sodium borohydride powder and silicone rubber compound (AB mix GEsilicones 42: RTV6166A silicone polymer and 6166B curing agent) andfilling and separating from a mold. A skin of silicone rubber 86 (GEsilicones RTV 118) 5 to 200 microns thick covers the second ampoule 82,86. In operation methanol and water are vaporized from the volatileampoule 89, 88 and diffuse through the open apertures of 79 and 81. Themethanol and water vapors diffuse to the chemical hydride ampoule 86, 82where they diffuse though the silicone rubber skin 86 and react with thesodium borohydride imbedded in the silicone rubber 82. Hydrogen gas 21is produced and diffuses into the rubber walled cavity 83. The hydrogengas leaves through the exit filter 85 made of expanded PTFE (CorningCostar) or hydrogen selective filter formed by coating an ultra filter(polyestersulfone PES; Pall Corporation, 2200 Northern Boulevard, EastHills, N.Y. 11548) with 5 nm of Pd, 50 nm 77% Pd/23% Ag alloy and a 5 nmfilm. The hydrogen then exits through the exit hose 84 to the fuel cellor hydrogen consuming device. The internal pressure of the hydrogen ifhigher than the outside pressure will put the rubber container walls 83in tension and subsequently pull the diaphragm apertures 79 and 81closer together. The ring seal 87 will progressively close off thediffusion route from aperture 79 to 81 as the pressure rises. If thepressure is high enough the tension in the wall 83 will cause the ringseal 87 to seal off. Details of this operation of the apertures areshown in FIG. 9 and 10. In FIG. 9 the inlet aperture 75 is a hole, orholes, in the center area of a entrance wall diaphragm 92. The exitapertures 78 are arranged along the perimeter of the exit wall diaphragm93. When the pressure is low the gas can freely diffuse through theapertures 75, 78. When the pressure is high, as shown in FIG. 10, thetension in the wall 83 pulls the aperture diaphragms 92, 93 together andcauses the ring seal 77 to make a seal. By sealing or partially sealingthe ring seal 77, the diffusion of reactants through the apertures 75and the exit apertures 78 is fully or partially reduced.

[0074]FIG. 11 shows a scheme in which liquid reactants are held incapillary tubes in one ampoule and are forced into contact with ahydrophobic encapsulated chemical hydride ampoule via feedbackcontrolled gas pump. In this particular form an ampoule of one liquidreactant held in capillary wick 102 and a chemical hydride ampoule 98are both placed and sealed in a reaction chamber 95. The reactionchamber forms gas tight seals 97 on the ampoules and at the access seal96. The chemical hydride ampoule 98 is formed by mixing sodiumborohydride powder with silicone rubber (AB mix GE silicones 42:RTV6166A silicone polymer and 6166B curing agent). This ampoule could bemade to have exit and channels 101 interdigitated through the ampoule toform high surface diffusion contact throughout the ampoule and liquidfree gas exit routes. The liquid reactant ampoule is formed as a bundleof capillary tubes with apertures smaller than 1 mm in diameter, made ofmaterials such as PVC (polyvinylchloride) or polyethylene and treated tobe hydrophilic. The liquid reactants, methanol and water, are wickedinto the capillary tubes 103. These capillary tubes 103 could alsoconsist of one long tube coiled and fused to form a compact ampoule withone opening on the pump side and one on the chemical hydride side. Theother component of the system is a pressurizing pump 104, of thediaphragm or centripetal impeller type, which is electrically driven bythe output of the fuel cell. It should be mentioned that an alternativescheme is to locate liquid pump 104 between the ampoules and pump theliquid reactant from the capillary ampoule 102 to the chemical hydrideampoule 101. Electronic controls can be used to control the output ofthe pump 104 to control the need for generated hydrogen 21. A filter 100such as porous expanded PTFE (Corning Costar) to prevent liquidreactants from flowing into the fuel cell or the hydrogen consumingdevice is placed to cover the hydrogen exit port 99. The operation ofthis system consists of pressurizing gas 94 with the input pump 104; theelectrical energy to run the pump could come from a capacitor charged byprevious operation of the fuel cell. The inlet gas for the pump 104could be obtained from the atmosphere or from the fuel vent exit of thefuel cell. When the pressure difference occurs across the capillary wickampoule 102 the liquid in the capillary tubes 103 is pushed toward thechemical hydride ampoule 98. Vapor diffusion to the chemical hydrideampoule 98 could be sufficient for low hydrogen generation rates. Thepressure from the generated hydrogen will push the liquid reactants backinto the capillary tubes 103. For higher generation rates the liquidfrom the capillary tubes 103 makes contact with the chemical hydrideampoule 98. The liquid reactants flow into the flow channels 101 of thesolid hydride 98. Once the liquid reactants are in the flow channels101, bubbles will form in the liquid reactants and tend to push theliquid reactant through the open channels 103. With closed end channelsthe liquid will be bubbled out and will pressurize the area between theampoules 102 and 98. Both closed and open flow channels 101 may beneeded to achieve smooth and responsive reactions with the chemicalhydrides and volatile reactants. The hydrogen 21 produced in thechemical hydride ampoule 98 diffuses and flows out of the channels 101.The hydrogen gas 21 is filtered of liquid reactants by the exit filter100, and hydrogen gas 21 is delivered out of the exit port 99 and to afuel cell or hydrogen consuming device.

[0075] While the invention has been described with reference to specificembodiments, modifications and variations of the invention may beconstructed without departing from the scope of the invention, which isdefined in the following claims.

We claim:
 1. A fueling apparatus, comprising at least two fuel bearingcontainers placed in close proximity to each other for moving fluid fromat least one container into at least one other container for generatinga hydrogen bearing fuel with at least one other container, and movingthe hydrogen bearing fuel from the at least one other container to anexit.
 2. The apparatus of claim 1, wherein at least one of the fuelcontainers contains one or more chemical hydrides.
 3. The apparatus ofclaim 1, wherein at least one of the fuel containers contains one ormore reactive solids.
 4. The apparatus of claim 1, wherein at least oneof the fuel containers contains one or more volatile reactants.
 5. Theapparatus of claim 1, wherein walls of the fuel containers are permeableto one or more volatile reactants.
 6. The apparatus of claim 1, whereinwalls of the fuel containers are selectively permeable to one or morevolatile reactants.
 7. The apparatus of claim 1, wherein walls of thefuel containers are made of silicone rubber or polymers that exhibit lowpermeability to water and high relative permeability to other reactants.8. The apparatus of claim 1, wherein walls of the fuel containers aremade of silicone rubber or polymers that exhibit low permeability towater and high relative permeability to methanol, formaldehyde, carbondioxide, acetic acid, or formic acid.
 9. The apparatus of claim 1,wherein at least one of the fuel containers contains one of the chemicalhydrides of LiH, LiAlH₄, LiBH₄, NaH, NaAlH₄, NaBH₄ MgH₂, Mg(BH₄)₂, KH,KBH₄, CaH₂, or Ca (BH₄)₂.
 10. The apparatus of claim 1, wherein walls ofthe fuel containers are made of silicone rubber or polymers that exhibitlow permeability to water and high relative permeability to methanol,carbon dioxide, sulfuric acid, acetic acid, or formic acid and one ofthe fuel containers contains one of the metals of Li, Na, K, Rb, Al, orCa.
 11. The apparatus of claim 1, further comprising a reaction controlmechanism adjacent the containers for regulating mass flow of reactantsbetween the containers.
 12. The apparatus of claim 1, further comprisinga reaction control mechanism for regulating mass flow of reactantsbetween the containers based on response to consumption or pressure ofproduced hydrogen.
 13. The apparatus of claim 1, further comprising anadjuster connected to the containers, wherein fuel diffusion from atleast one fuel container is adjusted electrically or mechanically. 14.The apparatus of claim 1, further comprising a reaction controlmechanism regulating mass flow of reactants between the containers basedon response to consumption or pressure of the produced hydrogen, whichconsists of valves, valves mechanically linked to the tension in thecontainer walls, moveable apertures, pumps, fans, ion drag membranes andchanging diffusion lengths.
 15. The apparatus of claim 1, wherein thehydrogen-bearing fuel is hydrogen gas used in a fuel cell.
 16. Theapparatus of claim 15, wherein the produced hydrogen gas is filteredthrough a filter.
 17. The apparatus of claim 15, wherein the producedhydrogen gas is filtered through a selectively permeable filter.
 18. Theapparatus of claim 1, further comprising a mass flow conduit forconducting a mass flow back to the containers from a consuming device.19. The apparatus of claim 1, wherein each fuel bearing containercomprises two or more types of fuel ampoules which, when used, areremoved from fuel impermeable containers and placed in proximity to theother type of fuel ampoule and a fuel cell, and a cover is replaced toform a fuel diffusion (manifold) plenum that has fuel in it andrestricts or excludes air exchange with the plenum.
 20. The apparatus ofclaim 1, wherein products from a hydrogen consuming device react withfuel in the fuel bearing containers for supplementing or intensifyinghydrogen production reaction between the fuel in the fuel bearingcontainers.
 21. The apparatus of claim 1, wherein products or water orcarbon dioxide from a hydrogen consuming device react with fuel in thefuel bearing containers for supplementing or intensifying the hydrogenproduction reaction between the fuel in the fuel bearing containers. 22.The apparatus of claim 1, wherein products or water or carbon dioxidefrom a hydrogen consuming device react with fuel in the fuel bearingcontainers for supplementing or intensifying hydrogen productionreaction between the fuel in the fuel bearing containers, andneutralizing a chemical hydride spent product.
 23. The apparatus ofclaim 1, wherein the fuel bearing containers comprise fuel ampoules, andwherein the ampoules are placed in an openable container that whensealed permits fuel in the ampoules to react with each other to producehydrogen.
 24. The apparatus of claim 23, further comprising additives inthe fuel ampoules for causing an appearance change and indicatingquantity of fuel in the fuel ampoules.
 25. The apparatus of claim 23,wherein the fuel ampoules appearance changes as the fuel is consumed.26. The apparatus of claim 23, further comprising additives in at leastone ampoule for enhancing, catalyzing, humidifying, or providing anacidified gas stream to a consuming device.
 27. The apparatus of claim23, wherein selective permeabilities of the ampoules have a temperaturedependent permeability to feeding the hydrogen bearing fuel at optimumrates at different temperatures.
 28. The apparatus of claim 23, whereinthe ampoule walls are formed with layers or composite of materials. 29.The apparatus of claim 23, further comprising storage container wallsare formed in layers or composite materials.
 30. A hydrogen fuel gasgenerator, comprising: a first ampoule having a liquid stored thereinand having a first permeable membrane for passing a vapor from thereactant out through the first membrane; a second ampoule having asecond reactant therein and having a second permeable membrane forpassing vapor from the first ampoule through the second permeablemembrane into the second reactant, and for passing hydrogen outwardthrough the second permeable membrane into a container; and a hydrogenoutlet port in the container and a hydrogen conduit connected to theoutlet for delivering the hydrogen to a hydrogen consuming device. 31.The apparatus of claim 30, further comprising a filter positionedadjacent the outlet port for permitting hydrogen to flow out of theoutlet port.
 32. The apparatus of claim 31, wherein the filter is ahydrogen permeable polymer.
 33. The apparatus of claim 31, wherein thefilter is a hydrogen permeable metal film.
 34. The apparatus of claim30, further comprising an intermediate permeable membrane spanning thecontainer between the first and second ampoules.
 35. The apparatus ofclaim 30, further comprising a fuel cell connected to the hydrogenconduit as the hydrogen consuming device.
 36. The apparatus of claim 35,further comprising a channel connected to one of the ampoules from thefuel cell for returning elements and compounds from the fuel cell to oneof the ampoules.
 37. The apparatus of claim 30, further comprising anon-permeable membrane in the container between the first and secondampoules.
 38. The apparatus of claim 37, further comprising an openingin the non-permeable membrane, and wherein the second permeable membraneis flexible for moving toward and away from the non-permeable membranefor closing and opening the opening according to relative pressures onopposite sides of the non-permeable membrane.
 39. The apparatus of claim38, further comprising a foam plenum between the first ampoule and theimpermeable membrane, and a vent connected to the foam plenum forventing vapor from the first ampoule when the opening is closed.
 40. Theapparatus of claim 37, further comprising multiple openings in thenon-permeable membrane and multiple flaps for selectively opening andclosing the multiple openings.
 41. The apparatus of claim 37, whereinthe non-permeable membrane is a first non-permeable membrane, andfurther comprising a second non-permeable membrane positioned betweenthe first non-permeable membrane and the second ampoule, and a variablechamber between the first and second impermeable membranes, first andsecond openings in the first and second impermeable membranes, at leastone of the impermeable membranes being flexible and operable for movingtoward and away from the other impermeable membrane.
 42. The apparatusof claim 41, having first and second flaps extending in a same directionfor respectively opening and closing the first and second openings asthe at least one impermeable membrane is flexed for varying volume ofthe chamber.
 43. The apparatus of claim 41, wherein at least one of theimpermeable membranes has a rim extending toward the other impermeablemembrane for surrounding and blocking the openings in the otherimpermeable membrane from communicating with openings in the at leastone membrane for controlling flow of vapors toward the second membrane.